Water pressures in our network
Water is principally supplied for domestic purposes and Manx Utilities’ primary responsibility is to provide a reliable wholesome water supply to our customers. As part of improving this reliability of supply we are constantly aiming to achieve more consistent pressures in the system (to reduce the number of bursts and the leakage). Sometimes we do this by the installation of Pressure Reducing Valves (PRVs) and sometimes we do this by rezoning parts of the system. We have a plan to install another 19 PRVs in the next 2 years. This is in addition to the 65 PRVs that we have already installed and operating. Generally they are installed to reduce very high pressure to a manageable pressure.
When we install a new PRV we use a hydraulic model to tell us what pressure is needed at the installation point in order to ensure that none of our customers are adversely effected (in that they receive over 1bar of pressure at their point of supply). Sometimes we fit PRVs that will vary the pressure depending upon the flow conditions in the system.
We are aware that many installations have firefighting systems (sprinklers). Our advice with these is consistent, we recommend that developers install fire tanks and pumps and not rely on the public water supply. This is because of the criticality of the system and also because we do not guarantee a water supply 365/24/7. However we also know that sometimes developers choose not to do this and when we are aware of systems we try to take this into account.
Another issue is where developers build high rise buildings or large developments at the end of systems. Not so much of an issue currently in the Isle of Man but where we do have developments we try to work with the developers as much as we can to help with the process and if we can accommodate the addition to our system we do. If our infrastructure is not sufficient, and upgrade is required (be that pressure or flow) we expect a contribution.
We have made a commitment to the fire service to inform them when we make planned changes and they have resolved to keep a register.
In conclusion, we can never guarantee a pressure as circumstances cause pressure to change. However, we are aware of fire sprinkler systems and therefore we try, as much as we can, to make pressures available so long as it is not damaging to our infrastructure. We are fitting new PRVs in the next 2 years, but the impact on the system as a whole will be relatively small.